Cylinder head

ABSTRACT

The invention provides an exhaust system including a cylinder head having a plurality of exhaust ports. Integrally formed with the cylinder head are a plurality of independent and separate tubes. The tubes are cast, molded or otherwise integrally formed with the exhaust ports of the cylinder head. The cylinder head and tubes eliminate the need for an exhaust flange, welding the tubes to the exhaust flange and securing the exhaust flange to the cylinder head. As a result, the present invention has less weight and improved performance over prior art cylinder head and exhaust assemblies.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.12/082,732 entitled “Cylinder Head,” filed on Apr. 14, 2008, and claimspriority from U.S. Provisional Patent Application No. 60/923,211entitled “Cylinder Head,” filed on Apr. 13, 2007, each of which arehereby incorporated by reference in their entirety.

FIELD OF THE INVENTION

This invention relates to a cylinder head of an internal combustionengine, and more particularly to a cylinder head with an improvedexhaust manifold connection.

BACKGROUND

In an internal combustion engine, the cylinder head is positioned on thetop of the engine block. The cylinder head provides upper portions ofeach combustion chamber, where each upper portion corresponds to onecylinder of the engine block. The cylinder head may house intake valves,exhaust valves, camshafts, rocker arms and pushrods, and numerous othermechanisms as known in the art.

An intake manifold and an exhaust manifold are typically coupled to thecylinder head. The intake manifold is located between the carburetor andcylinder head. In use, the intake manifold supplies an air-fuel mixturethrough internal intake ports in the cylinder head to each combustionchamber. In multi-port injected engines, the intake manifold holds fuelinjectors that supply an air-fuel mixture to each combustion chamber.

The exhaust manifold is typically coupled to the side of the cylinderhead opposite the intake manifold (i.e. the “exhaust side”). The exhaustmanifold collects exhaust gases exiting from each combustion chamberthrough internal exhaust ports in the cylinder head and transfers theseexhaust gases to an exhaust pipe of an exhaust system. The exhaustmanifold has a plurality of primary pipes in fluid communication with acommon exhaust pipe. Each primary pipe is coupled to the cylinder headover the outlet of a corresponding exhaust port such that each primarypipe collects exhaust gases exiting a corresponding combustion chamberand transfers them to the exhaust pipe.

The inlet end of each primary pipe is welded to a manifold inlet flange,which is subsequently bolted to the cylinder head. Since exhaustmanifolds are generally constructed of cast iron, the inlet flange isrelatively heavy and adds a substantial amount of weight to the engine.In addition, welding the primary pipes to the flange is difficult andcomplicated as it is necessary to provide a weld about the circumferenceof each pipe. Since there are usually a number of pipes, adjacent pipesinterfere with each other during welding. Thus, welding about the entirecircumference of each tube is difficult, expensive and time consuming.

Furthermore, once the primary pipes are welded to the flange, a separatemachining or smoothing of the flange is required in order to ensure thatthe cylinder head contacting surface of the flange is smooth and flat,thereby allowing for the secure formation of a sealing attachment of theflange to the cylinder head. The exhaust side of the cylinder headrequires similar machining or smoothing in order to provide acorresponding smooth and flat contacting surface of the cylinder head.Since the machining of these materials is difficult and time consuming,the overall cost of producing the engine is higher. Moreover, even withthe machining or smoothing of the surfaces, a manifold gasket isrequired to ensure a good seal between the cylinder head and exhaustmanifold. Further, this manifold gasket adds additional weight to theengine, and, over time, the manifold gasket may fail requiring expensivereplacement.

Consequently, there exists a significant need for a cylinder head whichwill provide a reduction in overall engine manufacture time and cost aswell as a reduction in engine weight.

DESCRIPTION OF THE DRAWING

The accompanying drawing, which is incorporated in and constitutes apart of this specification, illustrates an embodiment of the invention,and, together with the detailed description of the embodiment givenbelow, serves to explain the principles of the present invention, and inwhich:

FIG. 1 illustrates a perspective view of an embodiment of an exhaustside of a cylinder head in accordance with the present invention.

DETAILED DESCRIPTION

Referring now to FIG. 1, an exhaust side 15 of a cylinder head 10 isshown. The cylinder head 10 is positionable atop cylinders of thecombustion chambers of an engine (not shown). The cylinder head 10 isimportant to the performance of the engine as the shape of thecombustion chamber, inlet passages and exhaust determine the efficiencyof the engine.

Tubes 20 extend from the exhaust side 15 of the cylinder head 10. Eachtube 20 provides fluid communication between an exhaust port 17 of thecylinder head 10 and a primary pipe of an exhaust manifold such thatexhaust gases exiting the cylinder head 10 are transferred through thetubes 20 into the exhaust manifold (not shown).

In a preferred embodiment, the tubes 20 are integrally formed with thecylinder head 10. For example, the tubes 20 may be cast into the exhaustside 15 of the cylinder head 10. Advantageously, casting or otherwiseintegrally forming the tubes 20 with the cylinder head 10 eliminates theneed for a manifold gasket. In addition, integrally forming the tubes 20into the cylinder head 10 eliminates the need to weld each of the tubes20 to the manifold flange and secure the manifold flange to the cylinderhead 10. Accordingly, integrally forming the tubes 20 with the cylinderhead 10 provides a manufacturing cost savings over prior art cylinderheads and manifold assemblies.

Each of the tubes 20 may be integrally formed with one of the exhaustports 17 of the cylinder head 10 such that each combustion chamber ofthe engine corresponds to one of the tubes 20. As a result, the tubes 20provides less stress on the cylinder head 10 than the prior art tubesthat are bonded to a flange and bolted to the cylinder head 10. Theperformance of the engine is also improved over the prior art as theinterior of the tubes 20 can remain smoother. For example, in the priorart, the tubes 20 are welded to a manifold flange resulting in at leasta portion of the weld pool blocking exhaust flow through the tubes 20.Therefore, the tubes 20 of the present invention have a smootherinterior and increased performance over prior art cylinder head and tubeassemblies.

The tubes 20 may be constructed of metal or a metal alloy, such as, castiron, cast aluminum, a composite material, or the like. The interior ofeach tube 20 may be machined so as to provide a smoother interiorsurface to reduce energy loss due to wall friction and thereby increaseefficiency and engine performance. Also, as shown in FIG. 1, each tube20 may be substantially perpendicular to the exhaust side 15 of thecylinder head 10; however, it will be appreciated that each tube 20 maybe at any suitable angle relative to the exhaust side 15 of the cylinderhead 10.

Additionally, as shown in FIG. 1, each tube 20 may have a circularcross-section; however, it will be appreciated that each tube 20 mayhave any suitable cross-section, such as elliptical, triangular,rectangular, square, hexagonal, octagonal or the like.

Forming independent tubes 20 may allow flexibility in system design; forexample, in one embodiment, the tubes 20 may be of substantiallydifferent lengths, cross-sections, and/or at different angles relativeto the exhaust side 15 as may required by the overall engine compartmentand packing design thereby allowing more flexibility in exhaust manifolddesign and arrangement. In addition, separate tubes 20 may act as longerrunners thereby permitting better flow separation and scavenging of theexhaust gases prior to the gases entering the exhaust manifold, whichmay increase overall engine performance. For example, the tubes 20 mayhave distinct lengths and each connect to the primary exhaust pipe atdifferent locations.

The distal end 30 of each of the tubes 20 is in fluid communication withand coupled to a corresponding primary pipe of the exhaust manifold.Each of the tubes 20 may be coupled to one another and the primary pipevia a clamp (e.g. band clamp, v-band, Torca™ clamp, etc.), welding,press fit, threaded fit, an adhesive, or in another manner as will beappreciated by a person of ordinary skill in the art. Further, thedistal end 30 of each of the tubes 20 may be flared so as totelescopically receive a corresponding primary pipe of the exhaustmanifold; alternatively, the distal end 30 of each of the tubes 20 maybe narrowed to be telescopically received by a corresponding primarypipe of the exhaust manifold.

A method for manufacturing and assembling a cylinder head 10 is alsoprovided. A user may cast, mold, die-cast, or otherwise integrally formthe tubes 20 to the cylinder head 10. The tubes 20 may havepredetermined lengths, each of the tubes 20 have similar lengths ofdifferent lengths. The tubes 20 may be connected to a primary pipe ofthe exhaust manifold such that exhaust gases exiting the cylinder head10 are passed through the tubes 20 and into the exhaust manifold.

Advantageously, integrally forming the tubes 20 to the cylinder head 10may eliminate the need for an inlet flange on the exhaust manifold andcorresponding machining required on the exhaust side 15 of the cylinderhead 10, as well as elimination of the manifold gasket, thereby and inpart, possibly reducing the number of potential leak paths in thesystem. Alternatively, the distal end 30 of each tube 20 may include aflange that may be coupled to a corresponding inlet flange of an exhaustmanifold.

Having shown and described the preferred embodiment, further adaptationsof the methods and systems described herein may be accomplished byappropriate modifications by one of ordinary skill in the art withoutdeparting from the scope and principles of the present invention.Several potential modifications will become apparent to those skilled inthe art. Accordingly, the scope of the present invention should beconsidered in terms of the following claim and is understood not to belimited to the details of the embodiment shown and described above.

1. A method of manufacturing an exhaust system comprising the steps of:selecting a length of each of a plurality of tubes; casting a cylinderhead with a plurality of exhaust ports formed therethrough and theplurality of tubes, wherein the cylinder head and the plurality of tubesare integrally formed and each of the tubes corresponds to one of theexhaust ports.
 2. The method of claim 1 wherein each of the tubes areindependently connected to one of the exhaust ports.
 3. The method ofclaim 2 further comprising the step of: connecting at least two of thetubes to an exhaust manifold.
 4. The method of claim 2 furthercomprising the step of: connecting all of the tubes to a primary pipe ofthe exhaust manifold.
 5. The method of claim 2 further comprising thestep of: machining an interior of at least one of the tubes to smoothenthe interior of at least one of the tubes.
 6. The method of claim 1wherein at least one of the tubes is perpendicular to the exhaust portsof the cylinder head.
 7. The method of claim 1 wherein all of the tubesare perpendicular to the exhaust ports of the cylinder head.
 8. Themethod of claim 1 wherein each of the tubes has a substantially circularcross-section.